New submission from YoSTEALTH <rit...@stealthcentral.com>:
import os
import ctypes
# Stdlib
# ------
def test_preadv_stdlib(path):
fd = os.open(path, os.O_RDWR | os.O_CREAT)
buffer = bytearray(10)
buffers = [buffer]
try:
length = os.preadv(fd, buffers, 0, os.RWF_NOWAIT)
# OSError: [Errno 95] Operation not supported
print('length:', length)
print('buffer:', buffer)
finally:
os.close(fd)
# Cyptes Libc
# -----------
class iovec(ctypes.Structure):
_fields_ = [('iov_base', ctypes.c_char_p), ('iov_len', ctypes.c_size_t)]
libc = ctypes.CDLL('libc.so.6')
def test_preadv_libc(path):
fd = os.open(path, os.O_RDWR | os.O_CREAT)
buffer = bytes(10)
buffers = (iovec*1)()
buffers[0].iov_base = buffer
buffers[0].iov_len = 10
try:
length = libc.preadv2(fd, buffers, len(buffers), 0, os.RWF_NOWAIT)
print('length:', length) # length: -1
print('buffer:', buffer) # buffer:
b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
finally:
os.close(fd)
# Test Run
# --------
def test():
path = '/dev/shm/test-preadv-in-ram-file'
# Test-1 stdlib implementation
try:
test_preadv_stdlib(path) # OSError: [Errno 95] Operation not supported
except OSError:
print('OSError is raised. This should not raise OSError')
# Test-2 custom ctype `libc` implementation
test_preadv_libc(path)
if __name__ == '__main__':
test()
This code is just to demonstrate working vs receiving an OSError in this
specific usage.
System: Linux 4.19.56-1-MANJARO
Python: 3.8.0b2
When the file in question is stored in ram ('/dev/shm') stdlib implementation
raises an OSError while libc version does not.
----------
messages: 347364
nosy: YoSTEALTH, pablogsal, vstinner
priority: normal
severity: normal
status: open
title: OSError preadv()
type: behavior
versions: Python 3.8
_______________________________________
Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue37509>
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